The aim of this study is to detect covert brain processes that underlie cognition and performance in human subjects, and the acute and chronic effects of ethanol upon such processes. Included is an extensive study in which we are examining brain processes in individuals with different family histories of alcoholism. A principal focus of these studies is the measurement of brain electrical potentials, which provide information regarding the timing and character of the constituent sensory, cognitive and motor elements that are the mechanisms underlying observable behavior. The study of the brain potentials also allows inference of the specific brain regions affected by ethanol. The brain electrical potentials are studied within a broad context provided by performance and psychometric data, and measurement within other psychophysiological response systems. We have obtained data which document a large number of acute and chronic effects of ethanol on specific brain functions, ranging from sensory input to motor control functions. Of particular interest is a finding that brain electrical and autonomic signs of alerting and orienting are enhanced by ethanol, in contrast to its depressant effect on most other functions. A similar effect was observed in a sample of chronic alcoholic, organic brain disorder patients. Such findings suggest that ethanol intoxication and alcoholic organic brain disease may be associated with a disinhibition or deregulation of orienting processes.